China claims high-altitude balloons from the United States have flown through its airspace without permission more than 10 times since the start of 2022. The US National Security Council denies the allegation.

Chinese Foreign ministry spokesperson Wang Wenbin made the comments in response to questions about three unidentified flying objects that were recently shot down over North America.

Washington says it brought down the most recent aircraft over Lake Huron on Sunday.

Wang said China had nothing to do with it. "We oppose any attempt to make up untrue things and smear China," he said.

Unidentified objects have also been spotted flying over Japan in recent years.

The incidents in the US have raised questions about how Japan should respond if a balloon enters its airspace.

The chief cabinet secretary says Self-Defense Force aircraft are empowered to use weapons to deal with threats.

He said, "In the theoretical case of an airspace violation by an unmanned aircraft, SDF planes can take measures to protect the people, if those measures are deemed necessary."

But defense officials say it is much harder to make such decisions in practice. They say the inability to communicate with unmanned aircraft, like balloons, makes it difficult to determine whether they are actually dangerous or not in the moment.